Composite structures are extensively used in aerospace and other applications due to their high strength-to-weight ratios and amenability to being fashioned in a variety of shapes and contours. In some applications, it may be necessary or desirable to stiffen or stabilize composite structures. One method of stiffening composite structures includes use of a hat stiffener, which has a stiffener cap from which extends a pair of spaced-apart stiffener webs. Stiffener flanges may extend outwardly from the stiffener webs for attachment to the composite structure. The stiffener may eliminate or reduce flexing and bending in the composite structure to which the stiffener is attached.
A stiffener having an elliptical end termination which reduces strain in and enhances stability of the stiffener is desirable for some applications.